Projection device

Abstract

A projector for multicolor images includes light sources, which emit light of different wavelengths. The projector uses additive mixing of colors of the light from said three light sources and the maximum luminous flux at the white point is limited by the maximum luminous flux of the first light source. the projector make a white balance adjustment by adjusting the intensity and/or on-state times of the light sources.

1 . A projection device comprising first, second and third light sources, which emit light of different wavelengths, wherein, by additive mixing of colors of the light from said three light sources, the maximum luminous flux at the white point is limited by the maximum luminous flux of the first light source, a color unit coupling the light from the light sources into an illumination channel, a light modulator device, which immediately follows the illumination channel and modulates the light from the light sources, and projection optics projecting the modulated light onto a projection surface, wherein the light modulator device comprises first and second light modulators as well as a color-splitting unit arranged preceding said light modulators, said color-splitting unit having the light from the illumination channel impinging thereon and directing the light from the first light source onto the first light modulator and the light from the second and third light sources onto the second light modulator, and wherein a color-combining unit, which directs the modulated light coming from the light modulators to the projection optics, and a control unit are provided, which causes the second light modulator to be illuminated with the light from the second and third light sources sequentially in time, and which effects a white balance adjustment via at least one of the intensity and on-state times of the light sources.  
   
   
       2 . The projection device as claimed in  claim 1 , wherein the control unit controls the application of the light from the light sources to the light modulators such that, at a given color temperature, a luminous flux limited by the luminous flux of the first light source is achieved at the white point.  
   
   
       3 . The projection device as claimed in  claim 1 , wherein the light sources each comprise light emitting diodes.  
   
   
       4 . The projection device as claimed in  claim 3 , wherein the light emitting diodes emit red, green and blue light.  
   
   
       5 . The projection device as claimed in  claim 1 , wherein the light modulators are each reflective light modulators and the color-splitting unit and the color-combining unit are the same unit.  
   
   
       6 . The projection device as claimed in  claim 1 , wherein the color unit couples light into the illumination channel, independently of the polarization of the light from the light sources, and comprising in the illumination channel a first polarization unit which imposes a different polarization condition on the light from the first light source than that of the light from the second and third light sources, wherein the color-splitting unit effects color splitting as a function of the polarization condition of the light.  
   
   
       7 . The projection device as claimed in  claim 1 , wherein the color unit is polarization-sensitive and the light from the first light source of the color unit is supplied with a different polarization condition than the light from the second and third light sources, and in which the color-splitting unit effects color splitting as a function of the polarization condition of the light.  
   
   
       8 . The projection device as claimed in  claim 6 , wherein the light modulators comprise polarization-sensitive light modulators.  
   
   
       9 . The projection device as claimed in  claim 7 , wherein the light modulators comprise polarization-sensitive light modulators.  
   
   
       10 . The projection device as claimed in  claim 1 , further comprising a second polarization unit, which converts the modulated light from the light modulators into the same polarization condition, between the color-combining unit and the projection optics.  
   
   
       11 . The projection device as claimed in  claim 1 , further comprising a first lens array between at least one of the light sources and the color unit, and focusing optics having positive refractive power between the color unit and the light modulators, wherein the first lens array and the focusing optics form a honeycombed condensor system.  
   
   
       12 . The projection device as claimed in  claim 11 , wherein the optical distance from the focusing optics to the first lens array and from the focusing optics to the light modulators respectively correspond to the focal length of the focusing optics.  
   
   
       13 . The projection device as claimed in  claim 11 , wherein the honeycombed condensing system comprises a second lens array between the first lens array and the corresponding light source.  
   
   
       14 . The projection device as claimed in  claim 13 , wherein the focal points of the lenses of the second lens array are located in the plane of the first lens array.  
   
   
       15 . The projection device as claimed in  claim 13 , wherein both lens arrays are provided as a first tandem lens array.  
   
   
       16 . The projection device as claimed in  claim 15 , wherein a second tandem lens array is arranged between the first tandem lens array and the light source.  
   
   
       17 . The projection device as claimed in  claim 11 , wherein at least one lens array comprises a cylinder lens array.  
   
   
       18 . The projection device as claimed in  claim 11 , wherein the focusing optics comprise a Fresnel lens.  
   
   
       19 . The projection device as claimed in  claim 11 , wherein the focusing optics comprise an aspheric lens.  
   
   
       20 . The projection device as claimed in  claim 11 , wherein the color unit comprises first and second combining units, with the first combining unit directing the light from the second and third light sources into a partial beam path extending from the first combining unit to the second combining unit, in which one of the lens arrays comprises a first microlens arrays arranged as common microlens array for the second and third light sources, and the second combining unit directs the light from the partial beam path and the light from the first light source into the illumination channel.  
   
   
       21 . The projection device as claimed in  claim 1 , wherein the color unit comprises a polarizing beam splitter.  
   
   
       22 . A projection device comprising: 
 a first, second and third light source, each light source emitting light of a different wavelength wherein, by additive mixing of colors of the light from the first, second and third light sources, maximum luminous flux at the white point is limited by the maximum luminous flux of the first light source;    a color unit coupling the light from the first, second and third light sources into an illumination channel;    a light modulator unit, immediately following the illumination channel; and    projection optics to project the modulated light onto a projection surface;    in which the light modulator unit comprises first and second light modulators and a color-splitting unit positioned preceding the first and second light modulators, the color-splitting unit having the light from the illumination channel impinging thereon and directing light from the first light source onto the first light modulator and light from the second and third light sources onto the second light modulator, and further comprising a color-combining unit, which directs modulated light coming from the first and second light modulators to the projection optics, and further comprising a control unit, which illuminates the second and third light sources sequentially in time, and which adjusts white balance via intensity, on-state times of the light sources or a combination of the foregoing.    
   
   
       23 . The projection device as claimed in  claim 22 , wherein the control unit controls the application of the light from the light sources to the light modulators such that, at a given color temperature, a luminous flux limited by the luminous flux of the first light source is achieved at the white point.  
   
   
       24 . The projection device as claimed in  claim 22 , wherein the light sources each comprise light emitting diodes.  
   
   
       25 . The projection device as claimed in  claim 24 , wherein the light emitting diodes emit red, green and blue light.  
   
   
       26 . The projection device as claimed in  claim 22 , wherein the light modulators are each reflective light modulators and the color-splitting unit and the color-combining unit are combined in the same unit.  
   
   
       27 . The projection device as claimed in  claim 22 , wherein the color unit couples light into the illumination channel, independently of the polarization of the light from the light sources, and comprising in the illumination channel a first polarization unit which imposes a different polarization condition on the light from the first light source than that of the light from the second and third light sources, wherein the color-splitting unit effects color splitting as a function of the polarization condition of the light.  
   
   
       28 . The projection device as claimed in  claim 22 , wherein the color unit is polarization-sensitive and the light from the first light source of the color unit is supplied with a different polarization condition than the light from the second and third light sources, and in which the color-splitting unit effects color splitting as a function of the polarization condition of the light.  
   
   
       29 . The projection device as claimed in  claim 27 , wherein the light modulators comprise polarization-sensitive light modulators.  
   
   
       30 . The projection device as claimed in  claim 28 , wherein the light modulators comprise polarization-sensitive light modulators.  
   
   
       31 . The projection device as claimed in  claim 22 , further comprising a second polarization unit, which converts the modulated light from the light modulators into the same polarization condition, between the color-combining unit and the projection optics.  
   
   
       32 . The projection device as claimed in  claim 22 , further comprising a first lens array between at least one of the light sources and the color unit, and focusing optics having positive refractive power between the color unit and the light modulators, wherein the first lens array and the focusing optics form a honeycombed condenser system.  
   
   
       33 . The projection device as claimed in  claim 32 , wherein the optical distance from the focusing optics to the first lens array and from the focusing optics to the light modulators respectively correspond to the focal length of the focusing optics.  
   
   
       34 . The projection device as claimed in  claim 32 , wherein the honeycombed condensing system comprises a second lens array between the first lens array and the corresponding light source.  
   
   
       35 . The projection device as claimed in  claim 34 , wherein the focal points of the lenses of the second lens array are located in the plane of the first lens array.  
   
   
       36 . The projection device as claimed in  claim 34 , wherein both lens arrays are provided as a first tandem lens array.  
   
   
       37 . The projection device as claimed in  claim 36 , wherein a second tandem lens array is arranged between the first tandem lens array and the light source.  
   
   
       38 . The projection device as claimed in  claim 32 , wherein at least one lens array comprises a cylinder lens array.  
   
   
       39 . The projection device as claimed in  claim 32 , wherein the focusing optics comprise a Fresnel lens.  
   
   
       40 . The projection device as claimed in  claim 32 , wherein the focusing optics comprise an aspheric lens.  
   
   
       41 . The projection device as claimed in  claim 32 , wherein the color unit comprises first and second combining units, with the first combining unit directing the light from the second and third light sources into a partial beam path extending from the first combining unit to the second combining unit, in which one of the lens arrays comprises a first microlens arrays arranged as common microlens array for the second and third light sources, and the second combining unit directs the light from the partial beam path and the light from the first light source into the illumination channel.  
   
   
       42 . The projection device as claimed in  claim 22 , wherein the color unit comprises a polarizing beam splitter.  
   
   
       43 . A method of additively mixing colors of light emitted from first, second and third light sources, each emitting light of a different wavelength when the maximum luminous flux at the white point is limited by the maximum luminous flux of the first light source, the method comprising the steps of: 
 coupling the light from the first, second and third light sources into an illumination channel with a color unit;    locating a light modulator unit, immediately following the illumination channel; and    locating projection optics to project the modulated light onto a projection surface;    including in the light modulator unit first and second light modulators and a color-splitting unit positioned preceding the first and second light modulators,    directing light from the illumination channel to the color-splitting unit and directing light from the first light source onto the first light modulator and light from the second and third light sources onto the second light modulator, and directing modulated light coming from the first and second light modulators to the projection optics, via a color-combining unit; and    utilizing a control unit to illuminate the second and third light sources sequentially in time, or to adjust white balance via intensity, on-state times of the light sources or a combination of the foregoing.    
   
   
       44 . The method as claimed in  claim 43 , further comprising the step of controlling the application of the light from the light sources to the light modulators such that, at a given color temperature, a luminous flux limited by the luminous flux of the first light source is achieved at the white point.  
   
   
       45 . The method as claimed in  claim 43 , wherein the light sources each comprise light emitting diodes.  
   
   
       46 . The method as claimed in  claim 43 , wherein the light emitting diodes emit red, green and blue light.  
   
   
       47 . The method as claimed in  claim 43 , further comprising the steps of selecting reflective light modulators as the light modulators and utilizing a single unit to act as both the color-splitting unit and the color-combining unit.  
   
   
       48 . The method as claimed in  claim 43 , further comprising the steps of coupling light into the illumination channel independently of the polarization of the light from the light sources, and including, in the illumination channel, a first polarization unit which imposes a different polarization condition on the light from the first light source than that of the light from the second and third light sources, wherein the color-splitting unit effects color splitting as a function of the polarization condition of the light.  
   
   
       49 . The method as claimed in  claim 43 , wherein the color unit is polarization-sensitive and further comprising the steps of supplying the light from the first light source of the color unit with a different polarization condition than the light from the second and third light sources, and color splitting as a function of the polarization condition of the light.  
   
   
       50 . The method as claimed in  claim 48 , wherein the light modulators comprise polarization-sensitive light modulators.  
   
   
       51 . The method as claimed in  claim 49 , wherein the light modulators comprise polarization-sensitive light modulators.  
   
   
       52 . The method as claimed in  claim 43 , further comprising the steps of converting the modulated light from the light modulators into the same polarization condition, between the color-combining unit and the projection optics by use of a second polarization unit.  
   
   
       53 . The method as claimed in  claim 43 , further comprising the steps of interposing a first lens array between at least one of the light sources and the color unit, and interposing focusing optics having positive refractive power between the color unit and the light modulators, such that the first lens array and the focusing optics form a honeycombed condensor system.  
   
   
       54 . The method as claimed in  claim 53 , further comprising the steps of adjusting the optical distance from the focusing optics to the first lens array and from the focusing optics to the light modulators respectively to correspond to the focal length of the focusing optics.  
   
   
       55 . The method as claimed in  claim 53 , further comprising the steps of inserting a second lens array between the first lens array and the corresponding light source in the honeycombed condensing system.  
   
   
       56 . The method as claimed in  claim 53 , further comprising the steps of locating the focal points of the lenses of the second lens array in the plane of the first lens array.  
   
   
       57 . The method as claimed in  claim 53 , wherein both lens arrays are provided as a first tandem lens array.  
   
   
       58 . The method as claimed in  claim 57 , further comprising the steps of locating a second tandem lens array between the first tandem lens array and the light source.  
   
   
       59 . The method as claimed in  claim 55 , wherein at least one lens array comprises a cylinder lens array.  
   
   
       60 . The method as claimed in  claim 43 , wherein the focusing optics comprise a Fresnel lens.  
   
   
       61 . The method as claimed in  claim 43 , wherein the focusing optics comprise an aspheric lens.  
   
   
       62 . The method as claimed in  claim 57 , further comprising the steps of equipping the color unit with first and second combining units, the first combining unit directing the light from the second and third light sources into a partial beam path extending from the first combining unit to the second combining unit, and selecting, for one of the lens arrays, a first microlens array arranged as common microlens array for the second and third light sources, and directing the light from the partial beam path and the light from the first light source into the illumination channel the second combining unit.  
   
   
       63 . The method as claimed in  claim 43 , wherein the color unit comprises a polarizing beam splitter.